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  • java + increasing performance and scalability

    - by varun
    Hi, below is the a code snippet, which returns the object of a class. now the object is basially comparing to some parameter in loop. my concern is what if there are thousands of objects in loop, in that case performance and scalability can be an issue. please suggest how to improve this code for performance part public Widget get(String name,int major,int minor,boolean exact) { Widget widgetToReturn = null; if(exact) { Widget w = new Widget(name, major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { if((w.getName().equals(wid.getName())) && (wid.getVersion()).equals(w.getVersion())) { widgetToReturn = w; break; } } } else { Widget w = new Widget(name, major, minor); WidgetVersion widgetVersion = new WidgetVersion(major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { WidgetVersion wv = wid.getVersion(); if((w.getName().equals(wid.getName())) && major == wv.getMajor() && WidgetVersion.isCompatibleAndNewer(wv, widgetVersion)) { widgetToReturn = wid; } else if((w.getName().equals(wid.getName())) && wv.equals(widgetVersion.getMajor(), widgetVersion.getMinor())) { widgetToReturn = w; } } } return widgetToReturn; }

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  • Kohana 3, problem with m2m data adding

    - by Marek
    Hello I posted this on official forum but with no result. I am getting :Undefined index: enrollment error when trying to save data. My pivot model: class Model_Enrollment extends ORM { protected $_belongs_to = array('page' => array(), 'menugroup' => array()); } Model_Page protected $_has_many = array('templates' => array(), 'menugroups' => array('through' => 'enrollment')); Model_Menugroup protected $_has_many = array('menuitems' => array(), 'pages' => array('through' => 'enrollment')); //Overriden save() method in Model_Menugroup: public function save() { if (empty($this->created)) { $this->created = time(); } parent::save(); $this->reload(); if (! $this->is_global) { if (! empty($this->groupOwnerPagesId) { $page = ORM::factory('page'); foreach($this->groupOwnerPagesId as $id) { $this->add('enrollment', $page->find($id)); } } } } I did: I corrected table names in pivot model by changing them to singular I even now using the same name for pivot table / model = enrollment. The same as in tutorial. Just in case So the pivot table has name 'enrollment' and has 2 columns: page_id , menugroup_id I tried to add pk in pivot table, but it changed nothing I tried to add/remove db relation between pages/menugroups and pivot table (InnoDB) but with no luck I tried save all data in controller, but with the same bad result:( I am still getting the same error: Undefined index: enrollment in ORM line: $columns = array($this-_has_many[$alias]['foreign_key'], $this-_has_many[$alias]['far_key']); Could somebody tell me, what can be else wrong? I have no other ideas:( Kind regards

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  • queued view updates not happening when performSelector afterDelay:0 used

    - by JosephH
    Hi all, I have an app that performs some calculations based on data arriving on a socket or local user interaction. I want to show an 'activity spinner' whilst the calculation happens. spinner = [[UIActivityIndiactorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; [spinner setCenter:self.view.center]; [self.view addSubview:spinner]; [spinner startAnimating]; [self performSelector:@selector(doCalcs) withObject:nil afterDelay:0]; This works well, except in the case where the code is run as a result of a message arriving over the network. I'm using http://code.google.com/p/cocoaasyncsocket/ to handle sockets and the code is running in the onSocket:didReadData:withTag: method. 'doCalcs' takes a few seconds. The spinner doesn't appear whilst it's running. If I change afterDelay:0 to afterDelay:1 then the spinner does appear the whole time doCalcs is running, but with the downside that it takes an extra second. So it seems the code is all correct, but for whatever reason the spinner isn't getting a chance to get on screen before doCalcs runs. Any suggestions would be most welcome.

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  • Pick up relevant information from a string using regular expression C#3.0

    - by Newbie
    Hi, I have a situation. I have been given some file name which can be like <filename>YYYYMMDD<fileextension> some valid file names that will satisfy the above pattern are as under xxx20100326.xls, xxx2v20100326.csv, x_20100326.xls, xy2z_abc_20100326_xyz.csv, abc.xyz.20100326.doc, ab2.v.20100326.doc, abc.v.20100326_xyz.xls In what ever be the above defined case, I need to pick up the dates only. So for all the cases, the output will be 20100326. I am trying to achieve the same but no luck. Here is what I have done so far string testdata = "x2v20100326.csv"; string strYYYY = @"\d{4}"; string strMM = @"(1[0-2]|0[1-9])"; string strDD = @"(3[0-1]|[1-2][0-9]|0[1-9])"; string regExPattern = @"\A" + strYYYY + strMM + strDD + @"\Z"; Regex regex = new Regex(regExPattern); Match match = regex.Match(testdata); if (match.Success) { string result = match.Groups[0].Value; } I am using c#3.0 and dotnet framework 3.5 Please help. It is very urgent Thanks in advance.

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  • Where to add an overloaded operator for the tr1::array?

    - by phlipsy
    Since I need to add an operator& for the std::tr1::array<bool, N> I wrote the following lines template<std::size_t N> std::tr1::array<bool, N> operator& (const std::tr1::array<bool, N>& a, const std::tr1::array<bool, N>& b) { std::tr1::array<bool, N> result; std::transform(a.begin(), a.end(), b.begin(), result.begin(), std::logical_and<bool>()); return result; } Now I don't know in which namespace I've to put this function. I considered the std namespace as a restricted area. Only total specialization and overloaded function templates are allowed to be added by the user. Putting it into the global namespace isn't "allowed" either in order to prevent pollution of the global namespace and clashes with other declarations. And finally putting this function into the namespace of the project doesn't work since the compiler won't find it there. What had I best do? I don't want to write a new array class putted into the project namespace. Because in this case the compiler would find the right namespace via argument dependent name lookup. Or is this the only possible way because writing a new operator for existing classes means extending their interfaces and this isn't allowed either for standard classes?

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  • Image creation performance / image caching

    - by Kilnr
    Hello, I'm writing an application that has a scrollable image (used to display a map). The map background consists of several tiles (premade from a big JPG file), that I draw on a Graphics object. I also use a cache (Hashtable), to prevent from having to create every image when I need it. I don't keep everything in memory, because that would be too much. The problem is that when I'm scrolling through the map, and I need an image that wasn't cached, it takes about 60-80 ms to create it. Depending on screen resolution, tile size and scroll direction, this can occur multiple times in one scroll operation (for different tiles). In my case, it often happens that this needs to be done 4 times, which introduces a delay of more than 300 ms, which is extremely noticeable. The easiest thing for me would be that there's some way to speed up the creation of Images, but I guess that's just wishful thinking... Besides that, I suppose the most obvious thing to do is to load the tiles predictively (e.g. when scrolling to the right, precache the tiles to the right), but then I'm faced with the rather difficult task of thinking up a halfway decent algorithm for this. My actual question then is: how can I best do this predictive loading? Maybe I could offload the creation of images to a separate thread? Other things to consider? Thanks in advance.

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  • Clarification/explanation of RegisterClientScriptInclude method

    - by mpminnich
    I've been looking on the Internet for a fairly clear explanation of the different methods of registering javascript in an asp.net application. I think I have a basic understating of the difference between registerStartupScript and registerClientScriptBlock (the main difference being where in the form the script is inserted). I'm not sure I understand what the RegisterClientScriptInclude method does or when it is used. From what I can gather, it is used to register an external .js file. Does this then make any and all javascript functions in that file available to the aspx page it was registered on? For example, if it was registered in the onLoad event of a master page, would all pages using that master page be able to use the javascript functions in the .js file? What problems would arise when trying to use document.getElementById in this case, if any? Also, when it is necessary/advantageous to use multiple .js files and register them separately? I appreciate any help you can give. If you know of any really good resources I can use to get a thorough understanding of this concept, I'd appreciate it!

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  • Removing specific tags in a KML file

    - by Legion
    I have a KML file which is a list of places around the world with coordinates and some other attributes. It looks like this for one place: <Placemark> <name>Albania - Durrës</name> <open>0</open> <visibility>1</visibility> <description>(Spot ID: 275801) show <![CDATA[<a href="http://www.windguru.cz/int/index.php?go=1&vs=1&sc=275801">forecast</a>]]></description> <styleUrl>#wgStyle001</styleUrl><Point> <coordinates>19.489747,41.277806,0</coordinates> </Point> <LookAt><range>200000</range><longitude>19.489747</longitude><latitude>41.277806</latitude></LookAt> </Placemark> I would like to remove everything except the name of the place. So in this case that would mean I would like to remove everything except <name>Albania - Durrës</name> The problem is, this KML file includes more than 1000 of these places. Doing this manually obviously isn't an option, so then how can I remove all tags except for the name tags for all of the items in the list? Can I use some kind of program for that?

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  • ASP.NET DynamicData: Whats happening during an update?

    - by Jens A.
    I am using ASP.NET DynamicData (based on LINQ to SQL) on my site for basic scaffolding. On one table I have added additional properties, that are not stored in the table, but are retrieved from somewhere else. (Profile information for a user account, in this case). They are displayed just fine, but when editing these values and pressing "Update", they are not changed. Here's what the properties look like, the table is the standard aspnet_Users table: public String Address { get { UserProfile profile = UserProfile.GetUserProfile(UserName); return profile.Address; } set { UserProfile profile = UserProfile.GetUserProfile(UserName); profile.Address = value; profile.Save(); } } When I fired up the debugger, I've noticed that for each update the set accessor is called three times. Once with the new value, but on a newly created instance of user, then once with the old value, again on an new instance, and finally with the old value on the existing instance. Wondering a bit, I checked with the properties created by the designer, and they, too, are called three times in (almost) the same fashion. The only difference is, that the last call contains the new value for the property. I am a bit stumped here. Why three times, and why are my new properties behaving differently? I'd be grateful for any help on that matter! =)

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  • Large Switch statements: Bad OOP?

    - by Mystere Man
    I've always been of the opinion that large switch statements are a symptom of bad OOP design. In the past, I've read articles that discuss this topic and they have provided altnerative OOP based approaches, typically based on polymorphism to instantiate the right object to handle the case. I'm now in a situation that has a monsterous switch statement based on a stream of data from a TCP socket in which the protocol consists of basically newline terminated command, followed by lines of data, followed by an end marker. The command can be one of 100 different commands, so I'd like to find a way to reduce this monster switch statement to something more manageable. I've done some googling to find the solutions I recall, but sadly, Google has become a wasteland of irrelevant results for many kinds of queries these days. Are there any patterns for this sort of problem? Any suggestions on possible implementations? One thought I had was to use a dictionary lookup, matching the command text to the object type to instantiate. This has the nice advantage of merely creating a new object and inserting a new command/type in the table for any new commands. However, this also has the problem of type explosion. I now need 100 new classes, plus I have to find a way to interface them cleanly to the data model. Is the "one true switch statement" really the way to go? I'd appreciate your thoughts, opinions, or comments.

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  • Exporting to CSV/Excel in Java

    - by WIOijwww
    I'm trying to export data into a CSV file through Java and I've got some code to do it but it doesn't seem to be outputting the CSV file. Could someone tell me what's wrong? What I would like to do is rather than saving the file somewhere, I would like it to be directly exported to the user. EDIT: Just in case it's not clear, I don't want the file to be saved anywhere but would like it to be outputted automatically to the user i.e. they click export and get the "Run/Save results.csv" window and they open the file. Currently the file is getting saved so I know that the method seems to work, just in the opposite way that I want it to. public static void writeToCSV(List<Map> objectList) { String CSV_SEPARATOR = ","; try { BufferedWriter bw = new BufferedWriter(new OutputStreamWriter( new FileOutputStream("results.csv"), "UTF-8")); for (Map objectDetails : objectList) { StringBuffer oneLine = new StringBuffer(); Iterator it = objectDetails.values().iterator(); while (it.hasNext()) { Object value = it.next(); if(value !=null){ oneLine.append(value.toString()); } if (it.hasNext()) { oneLine.append(CSV_SEPARATOR); } } bw.write(oneLine.toString()); bw.newLine(); } bw.flush(); bw.close(); } catch (UnsupportedEncodingException e) { } catch (FileNotFoundException e) { } catch (IOException e) { } }

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  • JavaCC: How can I specify which token(s) are expected in certain context?

    - by java.is.for.desktop
    Hello, everyone! I need to make JavaCC aware of a context (current parent token), and depending on that context, expect different token(s) to occur. Consider the following pseudo-code: TOKEN <abc> { "abc*" } // recognizes "abc", "abcd", "abcde", ... TOKEN <abcd> { "abcd*" } // recognizes "abcd", "abcde", "abcdef", ... TOKEN <element1> { "element1" "[" expectOnly(<abc>) "]" } TOKEN <element2> { "element2" "[" expectOnly(<abcd>) "]" } ... So when the generated parser is "inside" a token named "element1" and it encounter "abcdef" it recognizes it as <abc>, but when its "inside" a token named "element2" it recognizes the same string as <abcd>. element1 [ abcdef ] // aha! it can only be <abc> element2 [ abcdef ] // aha! it can only be <abcd> If I'm not wrong, it would behave similar to more complex DTD definitions of an XML file. So, how can one specify, in which "context" which token(s) are valid/expected? NOTE: It would be not enough for my real case to define a kind of "hierarchy" of tokens, so that "abcdef" is always first matched against <abcd> and than <abc>. I really need context-aware tokens.

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  • Making IE "forget" information entered in form when using back button.

    - by typoknig
    I have a page with a form where many of the fields are populated from variables passed in the URL. Those fields are disabled (NON-EDITABLE) and are only there for the user to view. The remaining fields require user input and are NOT disabled (EDITABLE). When the form is submitted a confirmation page comes up. It may be the case that the user needs to submit several of these forms where the NON-EDITABLE information is identical from form to form, so being able to go back to the form page from the confirmation page would save a lot of time. The way I want this to work is when a user presses the back button all the NON-EDITABLE fields are populated, but the EDITABLE fields are blank. This is what Firefox is doing, but IE8 is does not "forget" what has been entered in the EDITABLE fields. To disable the cache the following appears at the beginning of my page AND at the end of my page. <head> <meta http-equiv="Pragma" content="no-cache"/> <meta http-equiv="Cache-Control" content="no-store"/> <head/> What more must I do to make IE forget what was entered in the EDITABLE fields when the back button is pressed? All of my pages are generated with PHP if that matters. EDIT: It appears to me that this is a problem of IE caching my page even though I have told it not to. Are my meta tags correct? Do I need to do something else to prevent IE from caching my page?

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  • .NET security mechanism to restrict access between two Types in the same project?

    - by jdk
    Question: Is there a mechanism in the .NET Framework to hide one custom Type from another without using separate projects/assemblies? I'm using C# with ASP.NET in a Website project. Note: I'm not talking about access modifiers to hide members of a Type from another type - I mean to hide the Type itself. Background: I'm working in an ASP.NET Website project and the team has decided not to use separate project assemblies for different software layers. Therefore I'm looking for a way to have, for example, a DataAccess/ folder of which I disallow its classes to access other Types in the same ASP.NET Website project. In other words I want to fake the layers and have some kind of security mechanism around each layer to prevent it from accessing another. Obviously there's not a way to enforce this restriction using language-specific OO keywords so I am looking for something else, for example: maybe a permission framework or code access mechanism, maybe something that uses meta data like Attributes. Even something that restricts one namespace from accessing another. I'm unsure the final form it might take. If this were C++ I'd likely be using friend to make as solution, which doesn't translate to C# internal in this case although they're often compared. I don't really care whether the solution actually hides Types from each other or just makes them inaccessible; however I don't want to lock down one Type from all others, another reason access modifiers are not a solution. A runtime or design time answer will suffice. Looking for something easy to implement otherwise it's not worth the effort ...

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  • Centering Divisions Around Zero

    - by Mark
    I'm trying to create something that sort of resembles a histogram. I'm trying to create buckets from an array. Suppose I have a random array doubles between -10 and 10; this is very simplified. I then want to specify a center point, in this case 0 and the number of buckets. If I want 4 buckets the division would be -10 to -5, -5 to 0, 0 to 5 and 5 to 10. Not that complicated right. Now if I change the min and max to -12 and -9 and as for 4 divisions its more complicated. I either want a division at -3 and 3; it is centered around 0 ; or one at -6 to 0 and 0 to 6. Its not that hard to find the division size = Math.Ceiling((Abs(Max) + Abs(Min)) / Divisions) Then you would basically have an if statement to determine whether you want it centered on 0 or on an edge. You then iterate out from either 0 or DivisionSize/2 depending on the situation. You may not ALWAYS end up with the specified number of divisions but it will be close. Then you iterate through the array and increment the bin count. Does this seem like a good way to go about this? This method would surely work but it does not seem to be the most elegant. I'm curious as to whether the creation of the bins and the counting from the list could be done in a clever class with linq in a more elegant way? Something like creating the bins and then having each bin be a property {get;} that returns list.Count(x=> x >= Lower && x < Upper).

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  • mod_rewrite failing on uppercase dir

    - by user1855277
    I have a very basic mod_rewrite in a .htaccess file which I'm sure worked last time I looked at it, but now it is doing strange things with the case of the REQUEST_URI. It's intended purpose is to rewrite sub-domains to a given file, passing the subdomain as a php var of bnurl. Here is my code: RewriteCond %{REQUEST_URI}= "RSDEV/location/" [NC] RewriteCond %{HTTP_HOST} . RewriteCond %{HTTP_HOST} !^www\. [NC] RewriteCond %{HTTP_HOST} ^([^.]+)\.mydomain\.co\.uk(:80)? [NC] RewriteRule ^RSDEV/location/$ RSDEV/newmain.php?bnurl=%1&accesstype=new [NC,L] Now, typing joebloggs.mydomain.co.uk/RSDEV/location/ into my web browser comes back with the response "The requested URL /RSDEV/location/ was not found on this server" which is a correct statement because /RSDEV/location/ is not a real directory, but why did it not rewrite to RSDEV/newmain.php?bnurl=joebloggs&accesstype=new as expected? Now, the really strange thing here is that if I enter joebloggs.mydomain.co.uk/rsdev/location/ into my browser (note rsdev is now lowercase), it correctly rewrites as expected. The script newmain.php is in dir RSDEV (uppercase) so if it was going to fail, I would have expected it to fail the other way round with the lowercase rsdev. As you can see, I have [NC] on each line. Is this my mod_rewrite code failing or some other mystical server force keeping me up all night?

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  • JavaScript array random index insertion and deletion

    - by Tomi
    I'm inserting some items into array with randomly created indexes, for example like this: var myArray = new Array(); myArray[123] = "foo"; myArray[456] = "bar"; myArray[789] = "baz"; ... In other words array indexes do not start with zero and there will be "numeric gaps" between them. My questions are: Will these numeric gaps be somehow allocated (and therefore take some memory) even when they do not have assigned values? When I delete myArray[456] from upper example, would items below this item be relocated? EDIT: Regarding my question/concern about relocation of items after insertion/deletion - I want to know what happens with the memory and not indexes. More information from wikipedia article: Linked lists have several advantages over dynamic arrays. Insertion of an element at a specific point of a list is a constant-time operation, whereas insertion in a dynamic array at random locations will require moving half of the elements on average, and all the elements in the worst case. While one can "delete" an element from an array in constant time by somehow marking its slot as "vacant", this causes fragmentation that impedes the performance of iteration.

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  • "end()" iterator for back inserters?

    - by Thanatos
    For iterators such as those returned from std::back_inserter(), is there something that can be used as an "end" iterator? This seems a little nonsensical at first, but I have an API which is: template<typename InputIterator, typename OutputIterator> void foo( InputIterator input_begin, InputIterator input_end, OutputIterator output_begin, OutputIterator output_end ); foo performs some operation on the input sequence, generating an output sequence. (Who's length is known to foo but may or may not be equal to the input sequence's length.) The taking of the output_end parameter is the odd part: std::copy doesn't do this, for example, and assumes you're not going to pass it garbage. foo does it to provide range checking: if you pass a range too small, it throws an exception, in the name of defensive programming. (Instead of potentially overwriting random bits in memory.) Now, say I want to pass foo a back inserter, specifically one from a std::vector which has no limit outside of memory constraints. I still need a "end" iterator - in this case, something that will never compare equal. (Or, if I had a std::vector but with a restriction on length, perhaps it might sometimes compare equal?) How do I go about doing this? I do have the ability to change foo's API - is it better to not check the range, and instead provide an alternate means to get the required output range? (Which would be needed anyways for raw arrays, but not required for back inserters into a vector.) This would seem less robust, but I'm struggling to make the "robust" (above) work.

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  • How often should network traffic/collisions cause SNMP Sets to fail?

    - by A. Levy
    My team has a situation where an SNMP SET will fail once every two weeks or so. Since this set happens automatically, we don't necessarily notice it immediately when it fails, and this can result in an inconsistent configuration and associated wailing and gnashing of teeth. The plan is to fix this by having our software automatically retry the SET when it fails. The problem is, we aren't sure why the failure is happening. My (extremely limited) knowledge of SNMP isn't particularly helpful in diagnosing this problem, so I thought I'd ask StackOverflow for some advice. We think that every so often a spike in network traffic will cause the SET to fail. Since SNMP uses UDP for communication, I would think it would be relatively easy for a command to be drowned out if traffic was high for a short period of time. However, I have no idea how common this is. We have a small network with a single cisco router and there are less than a dozen SNMP controlled devices on that network. In addition to the SNMP traffic, there are some status web pages being loaded from the various devices. In case it makes a difference, I believe we are using the AdventNet SNMP API version 4.0.4 for Java. Does it sound reasonable that there will be some SET commands dropped occasionally, or should we be looking for other causes?

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  • "date_part('epoch', now() at time zone 'UTC')" not the same time as "now() at time zone 'UTC'" in po

    - by sirlark
    I'm writing a web based front end to a database (PHP/Postgresql) in which I need to store various dates/times. The times are meant to be always be entered on the client side in the local time, and displayed in the local time too. For storage purposes, I store all dates/times as integers (UNIX timestamps) and normalised to UTC. One particular field has a restriction that the timestamp filled in is not allowed to be in the future, so I tried this with a database constraint... CONSTRAINT not_future CHECK (timestamp-300 <= date_part('epoch', now() at time zone 'UTC')) The -300 is to give 5 minutes leeway in case of slightly desynchronised times between browser and server. The problem is, this constraint always fails when submitting the current time. I've done testing, and found the following. In PostgreSQL client: SELECT now() -- returns correct local time SELECT date_part('epoch', now()) -- returns a unix timestamp at UTC (tested by feeding the value into the date function in PHP correcting for its compensation to my time zone) SELECT date_part('epoch', now() at time zone 'UTC') -- returns a unix timestamp at two time zone offsets west, e.g. I am at GMT+2, I get a GMT-2 timestamp. I've figured out obviously that dropping the "at time zone 'UTC'" will solve my problem, but my question is if 'epoch' is meant to return a unix timestamp which AFAIK is always meant to be in UTC, why would the 'epoch' of a time already in UTC be corrected? Is this a bug, or I am I missing something about the defined/normal behaviour here.

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  • How can you pass an object from the form_for helper to a method?

    - by Alex
    So let's say I have a form which is being sent somewhere strange (and by strange we mean, NOT the default route: <% form_for @form_object, :url => {:controller => 'application', :action => 'form_action_thing'} do |f| %> <%= f.text_field :email %> <%= submit_tag 'Login' %> <% end %> Now let's say that we have the method that accepts it. def form_action_thing User.find(????? :email ?????) end My questions are thus: How does can I make the object @form_object available to the receiving method (in this case, form_action_tag)? I've tried params[:form_object], and I've scoured this site and the API, which I have to post below because SO doesn't believe I'm not a spammer (I'm a new member), as well as Googled as many permutations of this idea as I could think of. Nothing. Sorry if I missed something, i'm really trying. How do I address the object, once I've made it accessible to the method? Not params[:form_object], I'm guessing.

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  • SYN receives RST,ACK very frequently

    - by user1289508
    Hi Socket Programming experts, I am writing a proxy server on Linux for SQL Database server running on Windows. The proxy is coded using bsd sockets and in C, and it is working just fine. When I use a database client (written in JAVA, and running on a Linux box) to fire queries (with a concurrency of 100 or more) directly to the Database server, not experiencing connection resets. But through my proxy I am experiencing many connection resets. Digging deeper I came to know that connection from 'DB client' to 'Proxy' always succeeds but when the 'Proxy' tries to connect to the DB server the connection fails, due to the SYN packet getting RST,ACK. That was to give some background. The question is : Why does sometimes SYN receives RST,ACK? 'DB client(linux)' to 'Server(windows)' ---- Works fine 'DB client(linux) to 'Proxy(Linux)' to 'Server(windows)' ----- problematic I am aware that this can happen in "connection refused" case but this definitely is not that one. SYN flooding might be another scenario, but that does not explain fine behavior while firing to Server directly. I am suspecting some socket option setting may be required, that the client does before connecting and my proxy does not. Please put some light on this. Any help (links or pointers) is most appreciated. Additional info: Wrote a C client that does concurrent connections, which takes concurrency as an argument. Here are my observations: - At 5000 concurrency and above, some connects failed with 'connection refused'. - Below 2000, it works fine. But the actual problem is observed even at a concurrency of 100 or more. Note: The problem is time dependent sometimes it never comes at all and sometimes it is very frequent and DB client (directly to server) works fine at all times .

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  • Java Inheritance doubt in parameterised collection

    - by Gala101
    It's obvious that a parent class's object can hold a reference to a child, but does this not hold true in case of parameterised collection ?? eg: Car class is parent of Sedan So public void doSomething(Car c){ ... } public void caller(){ Sedan s = new Sedan(); doSomething(s); } is obviously valid But public void doSomething(Collection<Car> c){ ... } public void caller(){ Collection<Sedan> s = new ArrayList<Sedan>(); doSomething(s); } Fails to compile Can someone please point out why? and also, how to implement such a scenario where a function needs to iterate through a Collection of parent objects, modifying only the fields present in parent class, using parent class methods, but the calling methods (say 3 different methods) pass the collection of three different subtypes.. Ofcourse it compiles fine if I do as below: public void doSomething(Collection<Car> c){ ... } public void caller(){ Collection s = new ArrayList<Sedan>(); doSomething(s); }

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  • Replacing/Adding resources (icon) programmatically in c#?

    - by reverendo
    I am trying to replace (or add in the case it doesn't exists) icons from .exe files using c#. So far I got this: string filename = "c:\\test.exe"; IntPtr hResource = BeginUpdateResource(filename, true); if (hResource.ToInt32() == 0) throw new Exception("File Not Found"); byte[] ico = System.IO.File.ReadAllBytes("C:\\icon.ico"); IntPtr unmanagedPointer = Marshal.AllocHGlobal(ico.Length); Marshal.Copy(ico, 0, unmanagedPointer, ico.Length); if (UpdateResource(hResource, "Icon", "1", 1033, unmanagedPointer, Convert.ToUInt32(ico.Length)) != false) { MessageBox.Show("Updated"); EndUpdateResource(hResource, false); } Marshal.FreeHGlobal(unmanagedPointer); "Icon", "1", 1033 <- I got this data by opening test.exe with Resource Hacker. I do get the messagebox "Updated", and if I open the resulting exe in Resource Hacker the resource gets replaced but the icon doesn't appear, its just empty. Also that code wont replace, the type "Icon" in the resource, it will delete everything and add that "Icon" and if I use BeginUpdateResource(path, false); it will not replace it neither but it will add ANOTHER "Icon". Where can I find an example to replace/add the icon using c# disregarding the name the resource use for the icon or if the resource doesn't exist?

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  • Passing C++ object to C++ code through Python?

    - by cornail
    Hi all, I have written some physics simulation code in C++ and parsing the input text files is a bottleneck of it. As one of the input parameters, the user has to specify a math function which will be evaluated many times at run-time. The C++ code has some pre-defined function classes for this (they are actually quite complex on the math side) and some limited parsing capability but I am not satisfied with this construction at all. What I need is that both the algorithm and the function evaluation remain speedy, so it is advantageous to keep them both as compiled code (and preferrably, the math functions as C++ function objects). However I thought of glueing the whole simulation together with Python: the user could specify the input parameters in a Python script, while also implementing storage, visualization of the results (matplotlib) and GUI, too, in Python. I know that most of the time, exposing C++ classes can be done, e.g. with SWIG but I still have a question concerning the parsing of the user defined math function in Python: Is it possible to somehow to construct a C++ function object in Python and pass it to the C++ algorithm? E.g. when I call f = WrappedCPPGaussianFunctionClass(sigma=0.5) WrappedCPPAlgorithm(f) in Python, it would return a pointer to a C++ object which would then be passed to a C++ routine requiring such a pointer, or something similar... (don't ask me about memory management in this case, though :S) The point is that no callback should be made to Python code in the algorithm. Later I would like to extend this example to also do some simple expression parsing on the Python side, such as sum or product of functions, and return some compound, parse-tree like C++ object but let's stay at the basics for now. Sorry for the long post and thx for the suggestions in advance.

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